Elbow mechanism heretofore known are provided with a latch locking mechanism placed in the arm portion of the mechanism. The locking mechanism is controlled by means of one control cable, the elbow flexion motion being effected by a control cable.
The aforementioned mechanism has many drawbacks and disadvantages. It requires two control movements from two separate units of the control harness. So, for instance, flexion of the elbow followed with locking in a chosen flexion position requires the following motions: unlocking the mechanism by pulling the control cable, flexion of the forearm by pulling a separate cable, and locking the mechanism by pulling again the locking cable. This control means is hard for a patient to master and at the same time it's execution was very troublesome. Another drawback consists in that the locking mechanism is located in the arm portion of the elbow and consequently cannot be used in the case of long arm stumps, eg., in the case of elbow disarticulation. Moreover, its range of application is also limited to a determined elbow size, this being different in case of children and adults. What is more, this mechanism can only be used either for a body powered arm or for a cosmetic passive limb coated with a body-like soft cover that is either for a prosthesis made with the use of extraskeletal or intraskeletal technique. Mechanical design heretofore used is both complicated and expensive.